Physical pharmacy

What type of flow is characterized by a decrease in viscosity with increasing shear stress?

• Bingham flow

• Dilatant flow

• Newtonian flow

• Pseudoplastic flow

What is the term for the phenomenon where a material slowly recovers its original viscosity after being sheared?

• Thixotropy

• Elasticity

• Viscosity

• Plasticity

What type of suspension has particles that repel each other?

• Deflocculated suspension

• Flocculated suspension

• Coarse suspension

• Colloidal suspension

What does a higher sedimentation volume indicate?

• Higher viscosity

• Worse physical stability

• No effect on stability

• Better physical stability

Which of the following is NOT a characteristic of flocculated suspensions?

• Form loose adhering systems

• Easily redispersed with gentle agitation

• Form a hard cake

• Particles settle slowly

Which type of emulsion typically creams upwards?

• Multiple emulsion

• Microemulsion

• O/W

• W/O

What is the main cause of breaking in emulsions?

• Phase inversion

• Insufficient emulsifying agent

• Separation of phases

• Flocculation

What is the main factor influencing the stability of colloids according to DLVO theory?

• Temperature

• Particle size

• Interparticle distance

• Concentration of solute

What is the primary reason for the instability of lyophobic colloids?

• Presence of solvent sheath

• High charge on particles

• Absence of charge

• Low molecular weight

What is the primary reason for the ageing of gels?

• Increased temperature

• Spontaneous aggregation

• Exposure to light

• Chemical reactions